Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. In use, an electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. The catheter should preferably be deflectable to permit proper positioning of the electrodes on its distal end within the heart.
Deflectable tip electrode catheters are well known. Such a catheter generally has a control handle at its proximal end for controlling deflection of the tip in one or more directions. For example, a particularly useful deflectable tip catheter is disclosed in U.S. Pat. No. Re. 34,502 to Webster, the disclosure of which is hereby incorporated by reference. This catheter comprises a puller wire that extends on-axis through an elongated reinforced catheter body and then off-axis in a deflectable tip portion. In this arrangement, longitudinal movement of the puller wire relative to the catheter body results in deflection of the catheter tip portion. Other examples of steerable catheters can be found in U.S. Pat. No. 5,431,168 to Webster entitled “Steerable Open-Lumen Catheter” and U.S. patent application Ser. No. 08/924,611 to Webster entitled “Omni-Directional Steerable Catheter,” the disclosures of which are hereby incorporated by reference.
One drawback to catheters and perhaps especially deflectable catheters is their tendency to shift from a treatment site in a patient's body when the catheter is released from a user's grip. Typically, when using a catheter the physician has to maintain his hold on the catheter in order to maintain the catheter's position in the patient's body. If the physician releases his hold, a suitable tissue site which has been located for treatment or evaluation, such as mapping, ablation or the like, can be easily lost with the slightest movement of the catheter. As such, the physician is often hampered by the need to maintain a hand on the catheter body during the course of the medical procedure. The problem may be greater with deflectable catheters which can store torsional energy and therefore readily unwind and shift when released from the doctor's grasp. With the heart chamber being a dynamic environment surrounded by moving tissue and blood flow, the ability to maintain the position of the catheter at the target site in a hands-free manner is most desirable.
Often with one hand already working the introducer or sheath, the physician may desire the ability to use that same hand to operate the catheter clamp. Moreover, it would therefore be desirable to bias the clamp toward a closed position so that clamping the catheter involves minimal action on behalf of the physician.